Guster got some help from an unlikely superfan during Thursday night’s concert at The Wiltern in Los Angeles.

After noting that the collaboration would be “weird and out of context,” the band invited pop star Kesha on stage to join them for “Happier,” a track from their 1999 album Lost and Gone Forever. Before going into the song, the pop singer and Ryan Miller took turns telling the story of how they met, with Kesha explaining that she was obsessed with the band during her childhood and that they’re her “fucking favorite.”

The sit in shouldn’t be that big of a surprise to fans that read the latest issue of Relix. The current March issue includes a feature on Guster that points out Kesha’s superfandom, with drummer Brian Rosenworcel recalling that “Kesha used to email me and I would sneak her into shows…Her email address was [email protected].”